The present invention relates to a stent with effective strut and connector patterns.
"Stent" is known in the art as a prosthesis or graft used for reinforcing the blood vessel, such as an artery, or for maintaining patency of the blood vessel after opening a stenosis in the artery, and has been effectively used in the vascular treatment in place of surgical exposing, incising, removing, replacing or bypassing a defected blood vessel required in the conventional vascular surgery.
The stent is generally formed into a cylindrical shape, and functions to support a part of the patient's blood vessel or another anatomical lumen from the inside thereof so as to maintain the patency of the artery or to reinforce a dissected arterial wall or like, which may impede a fluid passageway by collapse thereof. According to the recent clinical data, it has been reported that occurrence of re-stenosis can be greatly reduced by using the stent after opening the stenosis by the PTCA (percutaneous transluminal coronary angioplasty) balloon catheter.
In the conventional stents, the followings have been considered in constructing and using the stents. Firstly, in the balloon expandable type of the stent, the stent in a closed condition is mounted on a balloon attached at a distal end portion of a balloon catheter, and delivered to a lesion or stenosis through the patient's meandering artery over a guide wire preliminary introduced in the artery. In this respect, the stent should be flexible in order to be delivered through the narrow and meandering artery. On the other hand, the expanded stent should have enough strength to support the dissected arterial wall sufficiently or to keep opening stenosis. Therefore, it is desired that the stent is flexible, has a sufficient support structure, and can expand to have a large diameter.
Secondly, as disclosed in U.S. Pat. No. 5,669,932, when the stent is deployed by expanding the balloon of the balloon catheter, the entire length of the deployed stent becomes shorter than the length of the closed stent. The deployed length of the stent may be checked if it is adequate to cover a particular length of the stenosis. However, it is desirable to prevent shortening of the length of the expanded stent because the shortening may not cover the lesion as a doctor planed for the treatment.
Accordingly, one object of the invention is to provide a flexible stent which can be easily delivered through the meandering and narrow artery.
Another object of the invention is to provide the stent as stated above, which can substantially prevent shortening of the entire length of the stent when it is expanded.
A further object of the invention is to provide the stent as stated above, which can prevent twisting of the stent when it is expanded, to thereby prevent damage of cells due to twisting of the stent.
Further objects and advantages of the invention will be apparent from the following description of the invention.